It's not really a problem anymore. I went in to the city yesterday, and by some odd stroke of luck, HMV actually had a copy on cd! It's some 1990 reissue which has 4 bonus songs tacked on to the end. It's kind of lame, since it's not really the authentic album, but it has all the songs in the proper order, so that's cool.
I also bought a Mamas and the Papas greatest hits cd so I'll never have to listen to any cassette ever again.
+1 to me for thinking ahead.